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Marine Governors.

655

If, on the contrary, a heavy load is put on the engine, the
governor revolving at a low height gives the valve the utmost
travel, securing a late cut-off.

The Shaft governor provides automatic cut-off by a very
simple and compact arrangement, especially adaptable to small
high-speed engines. The gear of the Westinghouse engine is
shewn at () Fig. 652, the object being to directly vary the
eccentric throw. A A is a disc fixed to the crank shaft, having
pins B B for carrying centrifugal weights E E, and pin H for
supporting the eccentric H j. The latter may rock to the right or
left on pin H by a limited amount, to be determined by the
position of weights EE, their deviation causing an alteration in the
eccentric throw. The weights are connected by the link c D, so
that their movements shall be simultaneous, and are attached to
the eccentric by link F G. If the engines then revolve at a high
speed, the weights E E fly outward and pull the eccentric sheave
to the left, decreasing throw and producing early cut-off; if the
speed decreases, the strong springs K K bring the weights towards
the centre and increase the throw. (See p. 1145.)

Marine Governors have always been difficult to devise,
and, although no perfect governor exists, the arrangement at (a)
Fig. 652 is one of the best, acting as it does on a direct
principle. The fluctuations in speed of a marine engine are
caused by the propeller either partly or entirely leaving the water
rather suddenly, thus decreasing the load. The consequent
increase of speed or  racing' cannot be entirely obviated, but may
be considerably modified by the use of Dunlop's governor, c is
a large pipe communicating with the water near the propeller, and
D an air chamber which can be shut off from c by the screw-down
valve A, worked by hand-wheel B. F is a pipe containing only
air, the entrance of water being prevented by the baffle-plate E.
H is a diaphragm in communication with F, and L K. a rod which
partakes of the movement of H, transmitting it to the piston slidb
valve M, for admitting to or exhausting from cylinder p. The
cock L admits steam to M, and the piston rod Q R is connected to
the lever R s, which has its fulcrum at w. Finally, s T is a rod for
actuating a throttle valve in the high-pressure steam pipe of the
engine.